Unloading device



Aug 4, 1931- J; o. MCMILLAN 1,817,698

UNLOADING DEVICE Filed May 15, 1929 2 SheBt's-Sheeb l m l O n U) ux n: iF 8 0` .tv

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4 Aug.- 4, 1931. J. o. McMlLLAN 1,817,593

UNLOADING DEVICE l Filed May 15, 1929 2 Sheets-Sheet 2 4R 31a/vanter J.o. MCMizzmg Patented Aug. 4, 1531 l i .l .i l i. j; Y .l l

UNITED STATES JAMES OQMCMILLAN; or WICHITA, Kansas UNLOADING DEVICEAppuation filed my i5, 1929. serial No. 363,214.

This invention relates to improvements in on the movement of thecompressor piston for unloading devices for air or gas compressors,openin and closing the unloader. j and more particularly to a novelunloading Anot er object is to furnish an unloading device arranged inthe discharge pipe of the device designed to unload the discharge pipecompressor and controlled by pressure in the so rapidly as to cause theordinary check 55 compressorcylinder for automatically unvalve betweenthe receiver 'and thecompressor loading the discharge pipe between thecomto be instantaneously forced to its seat. Air presser and check valvewhenever the comcheck valves of the dash pot type, often fail pressorcomes to a stop. Such unloading deto seat, due to sticking caused by oilwaste vice facilitates the starting of the compressor or carbondeposits, which sticking results in 00 against the load, therebypreventing the many other troubles. burning of the motor andtransmission belt. Another object is to provide an automatic I haveheretofore proposed a combination unloading device of durable and ruggedconcheck valve and unloader operating in the struction, simple and cheapto manufacture,

l5 discharge pipe of the compressor, and actunon-sticking,noni-clogging, and positive in o5 ated by the variations in the flow ofair or gas action. 'y through the device; and the primary object It maybe stated further that most unof the present invention is to provide anunloading devices inuse todayrequire adjusting loading device which iscontrolled by the means to have the device accord with the pressure inthe compressor cylinder in startcompressor for which it is used. Asinexperi- 70 ing, and by reduction of pressure in the unenced operatorsdo not know how to properloading device back to the compressor cylin. lyadjust such devices, or the adjusting means der after the compressorcomesto a stop for themselves become loose, and get out of order,unloadingthe discharge pipe. this results in the device becomingclogged',

Another important object of my invention therefore, it is a furtherobject of this inven- 75 when used on small compressors, is to autotionto provide an unloading valve which is matically drain the watei` andoil Waste from fitted to the compressor and regulated autothe dischargeline each time the compressor matically by the flow of air through thesame, ceases its compressing operation. I am aware and which is notsensitive to clogging, due to that unloaders'of the bleeder type are inthe fact that it has a large bleeding port. 30

general use, but suoli unloaders have given With the foregoing objectsoutlined and considerable trouble. The pressure switch with otherobjects in view which will appear bleeder valve is the type mostgenerally in as the description proceeds,the invention conuse onautomatic motor driven compressor sists in the novel featureshereinafter deunits, and if the current fails or isswitched scribed indetail, illustrated in the accom- 85 oft while the installation is inoperation, the panying drawings, and more particularly pressure switchremainsl closed, due to the pointed out in the appended claims.

fact that the pressure has not been built up Referring-to the drawings,

to the cut-out point. Consequently,` the Fig. 1 is a side elevation of acompressor 10 bleeder valve remains closed and the comand receiver,shown combined with one yform 9o pressoris not unloaded. Subsequently,when of my improved unloader. the current is resumed, under suchconditions, Fig. 2 is an enlarged vertical sectional view, theinstallation. will start against full tank partly in elevation, of aportion of the unpressure, which causes blowing of fuses, buinloadingdevice.

ing or jumping of belts, and sometimes a more Fig. 3 is a horizontalsectional view. on the .95 expensive occurrence, a burned out motor. lline 3-3 of Fig. 2.

My invention eliminates the possibilities Fig. 4 isa similar view of amodification. ofthe above mentioned troubles, slnce the op- Fig. 5 is alongitudinal sectional view of eration of the unloading device isindependa special check valve forming part of the 5 ent of electricalmeans, and wholly dependent apparatus shown in Fig. 1| 10i In thedrawings, 6 designates the cylinder of an air or gas compressor 7, whichis driven by a motor 8, through the medium of a belt 9. The fluidcompressed by the piston (not- .shown) of the compressor, is forcedthrough the discharge pipe 10, into the receiver 11, and this dischargeline is preferably provided with a manually controlled valve 12 and acheck valve 13, the latter preventing any return of the compressed airor gas from the receiver to the compressor cylinder.

The parts 6 to 13 inclusive may be of conventional construction, and thepresent' improvements includes a T 14 which may beA chamber 15, as shownin Figs. 1 and 2, or

may be screwed directly into the T 14, as indicated at 19 in Fig. 4. vAport 20 inthe valve casing communicates .with a chamber 21 of thecasing, in which a valve 22 operates. While this' valve may be of anysuitable construction, it is preferably of the needle type, and itsconical end 23 cooperates with an annular valve seat 24 provided at oneend of the port 20. This valve has a disk 25 at one end which is pressedby a spring 26 against a flexible diaphragm 27 that is preferablyclamped in position against one end of the casing by means of a threadedcap 28 which has an internally threaded port into which one end of thepipe 17 is screwed. The chamber 21 of the valve casing is in constantcommunication with the atmosphere by means of a pipe 29. As shown inFig. 5, the pipe 17 is connected to the compressor cylinder by means ofa special check valve This check valve `is constructed to bleed inopposite directions. Its valve housing 37 has two valve seats 38 and 39which cooperate with a ball 40. In this form of the in'- vention eachvalve seat has a bleed groove 41, 42.' Consequently, with this form ofcheck valve, while the compressor is forcing air through the pipe 17into the chamber 36,

the passage of air will be delayed due to the bleed groove 41. On theother hand, during unloading, the groove 42 will restrict the passage ofair from the chamber 36, and somewhat retard the unloading.

As shown in Fig. 4, the pipe 17 is connected to the compressorcylinderby' means of another form of check valve 30a which includes a tubularhousing 31 that is internally threaded for connection with the pipe 17.This housing has an annular valve seat 32 that cooperates with a ball 33which is forced towards the seat by a coiled spring 34. A bleed groove35 extends along the bore of the housing from the valve seat toward theinterior of the cylinder 6 for the purpose of delaying the return of thepressure luid'from the chamber 26 of the unloader valve' to thecompressor cylinder.

In operation, it will be understood that the compressor 6 will force theair or gas through the discharge pipe 10, into the air receiver 11. Thepressure fluid will not alone be forced through the pipe 10, but it willimmediately be built up in the chamber 36 to close the valve 22 toprevent any bleedingof the air to atmosphere through the pipe 29, whilethe compressor is in action. While the compressor is in action,especially with small compressors, water and waste oil will gather inthe chamber 15, and my improved mechanism functions not alone to unloadthe compressor but to discharge such water and oil waste.

When the pressure in the receiver 11 reaches a predetermined degree, themotor 8 is automatically stopped by the usual cut-out means (not shown).Immediately when this occurs, the unloader comes into operation,

and the check valve 13 is instantly forced to its seat to prevent anyreturn of pressure fluid from the chamber 11 to the cylinder 6. As thecompressor comes to a halt, the pres# sure in the cylinder 6automatically lowers and consequently, the spring 26 forces the valve 22away from its seat, so that pressure fluid in the conduit 10 and chamber15 blows any water or oil waste out through the pipe 29 to atmosphere,and at the same time, it

yrelieves the system at the entrance side of the 'check valve 13 ofpressure fluid.

As shown in Fig. 5, the pressure fluid in passing from the chamber 36 tothe cylinder 6, will pass-through the bleed groove 42, and thus thereleasing of the oil from the chamber 36 will be retarded tothe desireddegree On small compressor units, it is important fto have what Aistermed an unloading chamber or cooler, and trap. This chamber traps muchofthe waste water and oil, it cushions the pulsations on the check valve13, it cools the oil somewhat, and acts as an unloading chamber in thatthe com ressor must turn vover several times before uilding up vmuch ofa pressure. In draining oil from this chamber, it has always beennecessary to do `so by opening a cock by hand. In my improvements, thisis done automatically each time the' compressor comes to a stop. Whenthe compressor comes to a stop, the valve 22 is unseated, and the fluidin the chamber 15 is forced out through the pipe 29. After the fluid hasbeen expelled, the air in the discharge line will also be released, andthe system unloaded, cleaned and ready to be started. When the unloadingchamber 15 is used, the

valve 22 will close on the first twoor three revolutions of thecompressor, due to the fact thatI there is too much air space to befilled,y and very little pressure being produced on the side of thediaphragm 27, next to the chanber 21.

My unloadingl valve indicated in its entirety by 16, made in one size,will operate successfully on several sizes of compressors, but after acertain size compressor, the 'unloading valve should be a size larger 1nproortion to the next sizes of compressors it 1s to be used on.

My unloader is simple, durable and of rugged construction. It is cheapto manufacture, dependable, positive in operation, comprises only a fewmoving parts, and can be easily assembled, even by an unskilled person.No adjustments are necessary with the same. There is no sticking, and noclogging. Furthermore, when it includes the chamber 15, the latter formsan automatic waste eliminator.-

The terms and expressions employed herein are used as terms ofdescription, and not of said line to the cylinder of the compressor, andan unloading valve interposed in said conduit and functioning due topressure change in the compressor cylinder to unload the compressor anddischarge line.

2. In an apparatus of the character described, a compressor cylinderhavinga discharge line, a receiver connected to said line, a check valveinterposed in said line for preventing pressure fluid from moving fromthe-receiver to the cylinder, a conduit connecting the cylinder to saidline and connected to the latter at a point between the check valve andthe cylinder, and unloader valve means interposed in said conduitl andfunctioning due to pressure change in the cylinder to release thepressure fluid from the discharge line and cylinder. f"

3. An apparatus as claimed in claim 2,

in which said conduit includes an unloader chamberfunctloning to gatherwastewater and oil from the discharge line, the valve means being soarranged relatively to the unloader chamber as to discharge any waterand oil waste from the unloader chamber when the unloader valve meansopens.

4. An apparatus as claimed in claim 2, including a check valve arranged'in said conhav. `ing a discharge line, a conduit connecting and cluding.a check valve interposed invsaid conduit between the vunloader valvemeans and the cylinder, and functioning to allow the lgradual flow ofpressure fluid from the valve means toward the cylinder.

V6."'An apparatus as claimed in claim 2, includinr a check valveinterposed Vin said conduit lbetween the unloader valve means and thecylinder, and functioning to restrict the flow of ressure fiuid from thevalve means towarthe cylinder, said last mentioned check valvecomprising a notched seat and a valve member cooperating with said seat.

7. An apparatus as claimed in claim 2, including a check Valve arrangedin said conduit between the unloader valve means and the cylinder, saidlast mentioned check valve including a housing provided with opposedseats; and a valve member interposed in the housing and cooperating withboth of said seats.

8. An apparatus as claimed in claim 2, including a check valve arrangedin said conduit between the unloader valve means and the cylinder, saidlast mentioned check valve including a housing provided with opposedseats, and a valve member interposed in the housing and cooperatino'with both of said seats, each of said seats low the flow of pressurefluid to pass the valve member when the valve member is seated.

. 9. An apparatus as claimed in claim 2, in which said unloader valvemeans includes a valve seat, a valve member cooperating with said seat,and a diaphragm cooperating with the valve member for forcing the sameagainst its seat.v

10. In an apparatus of the character described, an unloader valvehousing, a diaphragm arranged in the housing and dividing the interiorof the same into first and second chambers, a port to place the firstchamber in communication with a compressor discharge line, a valve seatfor said port, a valve member cooperating with said seat and adapted tobe forced against the latter by the diaphragm under fluid pressurecreated in the second chamber, and a second port communicating with thefirst chamber and' placing said first chamber in communication with theatmosphere.

11. In an apparatus of the character described, an unloader valvehousing including a body having a removable cap, a flexible diaphragmarranged in said housing and clamped in position by the cap, saiddiaphragm dividing the interior of the body into first and secondchambers, a port to admit pressure-Huid to the first chamber andprovided with a valve seat, a port to admit a pressure iuid to thesecond chamber, a valve 'being notched to ali member movable with saiddiaphragm and arran ed in the first chamber and cooperating with saidseat, said valve member functioning to move toward the diaphragm whenmoving away from said seat and another port placing the rst chamber incommunication with the atmosphere.

12. In an apparatus of the character described, a compressor cylinder, apressure fluid receiver, a'di'scharge pipe connecting the cylinder tothe receiver, a check valve interposed in said pipe for preventing theHow of pressure iuid from the receiver to the cylinder, an unloaderchamber' connected to the discharge lpipe at a oint between the checkvalve and the cylin er and arranged to receive any liquid draining fromthe discharge pipe, an unloader valve connected tothe lower end of theunloader chamber, and functioning to discharge air and gas from theunloader chamber, and a conduit placing said last mentioned valve incommumcation with the cylinder, whereby pressure created in the cylinderis used to close said unloader valve. 13. A compressor unloadercomprising a valve casing to be connected to the discharge of acompressor between the compressor and check valve, a diaphragm in thecasing, a cap clamping the diaphragm to the casing and so forming withthe latter up er and lower chambers, a valve member in t e upper chamberto open and close a port communicating the upper chamber with that ofthe compressor discharge, said casing having a second port communicatingthe upper chamber with the atmosphere, a pipe communicating the lowerchamber with the compressor cylinder, a check valve in said pipe, meanswithin the said check valve for automatically de- 0 laying the time forthe compressor to take the full load by permitting the air from thecompressor to escape to the atmos here through the unloading valve untilsu cient v speed has been attained to take the full load, whenever thecompressor comes to a stop, means being provided in the check valveconnected to the compressor cylinder for releasing pressure on thediaphragm of unloader to open a port communicating the compressor 5udischarge between the compressor and the discharge check valve toatmosphere as the compressor comes to a stop, and means for releasing anaccumulation of waste oil and water, a quick release of air from thedischarge line also forcing the discharge check valve to seat.

JAMES O. MGMILLAN.

